Field of the Invention
The invention is in the field of self-contained, portable breathing gas heating system to be used by a diver for submersion in a cold environment.
More specifically, the invention is in the field of methods of supplying heat to breathing gas by filling a heat exchanger with a preheated liquid just before the diver submerges in a cold marine environment whereby the breathing gas from the tank is heated for a short period of time, up to 3 hours, by heat exchange between the hot liquid and the gas passing from the tank through the heat exchanger to the diver's mouth in the conventional face mask. A predetermined amount of hot liquid in a relatively small amount provides adequate heat to permit the diver to do useful work safely and efficiently as long as the breathing gas had been preheated to a degree which permits the delivery of 100 BTU to 300 BTU per hour to the diver.